skewed: The decay produces a muon (a
cousin of the electron) and an antimuon
less often than it makes an electron and
a positron. In the standard model, those
rates should be equal, says Guy Wilkinson,
a physicist at the University of Oxford in the
United Kingdom and spokesperson for the
770-member LHCb team. “This measurement is of particular interest because theoretically it’s very, very clean,” he says.

The result is just one of half a dozen faint
clues LHCb physicists have found that all
seem to jibe. For example, in 2013, they examined the angles at which particles emerge
in such B meson decays and found that they
didn’t quite agree with predictions.

What all those anomalies point to is less
certain. Within the standard model, a B meson decays to a K meson only through a complicated “loop” process in which the bottom
quark briefly turns into a top quark before
becoming a strange quark. To do that, it has
to emit and reabsorb a W boson, a “force
particle” that conveys the weak force (see
graphic, previous page).

The new data suggest the bottom quark
might morph directly into a strange quark—
a change the standard model forbids—by
spitting out a new particle called a Z9
boson. That hypothetical cousin of the Z boson would be the first particle beyond the
standard model and would add a new force
to theory. The extra decay process would
lower production of muons, explaining the
anomaly. “It’s sort of an ad hoc construct,
but it fits the data beautifully,” says Wolfgang
Altmannshofer, a theorist at the University
of Cincinnati in Ohio. Others have proposed
that a quark–electron hybrid called a lepto-quark might briefly materialize in the loop
process and provide another way to explain
the discrepancies.

Of course, the case for new physics could
be a mirage of statistical fluctuations. Physicists with ATLAS and CMS 18 months ago
reported hints of a hugely massive new particle only to see them fade away with more
data (Science, 12 August 2016, p. 635). The current signs are about as strong as those were,
Altmannshofer says.

The fact that physicists are using LHCb
to search in the weeds for signs of something new underscores the fact that the
LHC hasn’t yet lived up to its promise.
“ATLAS and CMS were the detectors that
were going to discover new things, and
LHCb was going to be more complementary,” Matias says. “But things go as they go.”
If the Z9 or leptoquarks exist, then the
LHC might have a chance to blast them into
bona fide, albeit fleeting, existence, Matias
says. The LHC is now revving up after its
winter shutdown. Next month, the particle
hunters will return to their quest. j

Paleontologists have argued for years about the identity of the enigmatic urling shapes and embryolike spheres found in the 600-million- year-old rocks of the Doushantuo Formation in China. But some say
those fossils, no bigger than a grain of salt,
may be the remains of some of the world’s
first animals. Now researchers fear that
the rock formation may
be pulverized, along with
its cargo of fossils, before
scientists can identify
the creatures and what
they may reveal about the
evolution of animals. A
massive phosphate mining operation in southern
China threatens the site,
and scientists are urging
the Chinese government to
step in to protect it.

The mining operations,which produce raw ma-terial for fertilizer, arealready destroying unique fossil evidenceat a distressing rate, says Zhu Maoyan,fossil expert and professor at the Nan-jing Institute of Geology and Palaeontol-ogy in China. The site, with its mysteriousWeng’an biota, is located in rural Guizhou,a Chinese province bordering Vietnam.Piecemeal phosphate mining has takenplace there for years, but a large-scaleproject that began in 2015 could wipeout the entire site, including a wealth ofas-yet-undiscovered fossils—a “disaster[to] all human beings,” Zhu says. The min-ing project already has demolished one ofthe three key fossil sites, he says.

“If you want to know about how animalsevolved on Earth, this site is the most im-portant one we know of,” says David Bottjer,earth sciences professor at the University ofSouthern California in Los Angeles, who hasbeen visiting the Weng’an site to collect fos-sils since 1999, a year after their discovery(Science, 6 February 1998,p. 879). “If this fossil de-posit is lost, we will losethis unique window onevolution of life, which maynever be replaced.”Weng’an fossils—putativeembryos and occasionaladults—lived 30 millionyears before the oldestwidely accepted animals:the Ediacaran biota foundin Newfoundland, Canada,and other sites. Those seacreatures, which come inan array of bewilderingshapes, represent a lost era of life on Earth:They were later replaced during the Cam-brian Explosion, when animals with morefamiliar body plans burst onto the scene. Asprecursors to the Ediacara, the Doushantuofossils “provide an unparalleled window intothe early evolution of lineages leading to ani-mals and possibly [the evolution of ] animalsthemselves,” says Douglas Erwin, a paleo-biologist at the Smithsonian Museum ofNatural History in Washington, D.C.

Early animal fossils at riskMining operation in China threatens fossils and embryosthat may be the oldest known animalsPALEONTOLOGYBy Kathleen McLaughlin in Beijing

This tiny tubular creature, only half
a millimeter across, was unearthed
at the Weng’an site and may be the
world’s oldest sponge.